This invention relates to a container structure, and more particularly to improved means for automatically venting vapors arising from hot moist food in a closed container.
In containers such as paperboard cartons for containing hot foods, the cover or a wall of a carton typically is provided with vents such as punched-out holes, or cut and scored areas that are manually foldable inwardly to provide holes. Vents of this type, while effective to prevent certain foods from becoming soggy, often permit the food to cool before it is served, since the vents remain open. Automatic venting means have been provided in sealed cook-in cartons, and have involved generally the use of heat-fusible means operable to open and vent at the relatively high temperatures encountered in cooking or reconstituting frozen foods. Vent means of this latter type is of course somewhat impractical for relatively lower food-serving temperatures. Also, once opened these same vent means remain open.
It is a general objective of this invention to provide automatic vent means for vapors emanating from hot food in a closed container.
It is a further, more specific objective of the invention to provide an improved automatically openable vent means for a closed paperboard carton responsive to presence of vapors emanating from hot food in the carton, which vent means also is automatically closable upon cool-down of the food.